EP3540211A1 - Vortex generator for attachment to a wind energy assembly rotor blade - Google Patents

Abstract

A vortex generator having a longitudinal direction, two fins each disposed at an angle to the longitudinal direction and extending in the longitudinal direction over a first length, and a base connecting the two fins having a width and extending in the Extending longitudinally over a second length, wherein over the entire width of the base, the second length is smaller than the first length.

Description

The invention relates to a vortex generator for attachment to a wind turbine rotor blade. Vortex generators, sometimes referred to as vortex generators, are used in wind turbine rotor blades for a specific influencing of the flow conditions. They have two fins arranged at a distance from each other, each projecting from the surface of the rotor blade into a boundary layer of the flow and which are aligned at an angle to the direction of flow. If these fins are exposed to the incoming air in the operation of the rotor blade, this leads to the formation of high-energy vortices and downstream of the vortex generator to a turbulent boundary layer. In particular, in the leaf root area, it has been found useful in many cases to use this effect to avoid or delay flow separation. For this purpose, the vortex generators must be attached to appropriate positions on the leaf surface. This is usually done by sticking.

This attachment encounters considerable difficulties. Basically, there are high demands on the quality of the attachment, because during operation, the rotor blades of wind turbines are exposed to wind and weather for years and difficult to access for maintenance and repair work. In addition, the surface of the rotor blades has a curvature that changes continuously both in the direction of the blade depth, ie from the profile nose edge to the profile end edge, and in the longitudinal direction of the rotor blade, ie from the blade root to the blade tip.

An individual adaptation of the mounting surface of each vortex generator to the curvature of the surface of the rotor blade existing at the position of its intended attachment is impractical. Therefore, a plane surface or an area with a mean curvature is selected for the attachment surfaces of the vortex generators. The inevitable gaps must be filled up with glue become. This requires a relatively low viscosity adhesive that has low initial tack, so any vortex generator needs to be fixed until the adhesive provides adequate adhesion. Adhesive tapes do not represent a suitable alternative since they are only of limited suitability to compensate for different gap dimensions. The assembly of the vortex generators is therefore complicated and error-prone. In practice it can be observed again and again that individual vortex generators detach from the surface and eventually fall off.

From the publication EP 2 484 898 B1 Vortex generators have become known which have a curved mounting surface for adhering to the surface of a wind turbine rotor blade. The attachment surface comprises a large-area recess in which the adhesive is to be arranged, and a peripheral edge which is intended to protect the adhesive layer from external influences.

From the publication EP 2 799 709 B1 It has become known to attach vortex generators with an adhesive layer to a surface of a wind turbine rotor blade. The adhesive layer should have a low shear modulus to avoid delamination of the vortex generators upon rotor blade deformation.

From the publication EP 2 826 708 B1 Vortex generators have become known, which are attached with adhesive tapes to a surface of a wind turbine rotor blade. The vortex generators should be flexible, so that a mounting surface of the vortex generators can adapt to the contour of the rotor blade.

From the publication WO 2015/030573 A1 Vortex generators have become known with two fins, which are interconnected by a base plate. The fins have a slight curvature, which should increase flexibility of the base plate and allow adaptation of the base plate to different curvatures of the surface of the rotor blade. It is also proposed that Base plate U-, V-, or W-shaped form. This measure is intended to allow thermal expansion and at the same time be aerodynamically advantageous.

On this basis, it is the object of the invention to provide a vortex generator which can be attached to a surface of a wind turbine rotor blade in a particularly simple and reliable manner.

This object is achieved by the vortex generator having the features of claim 1. Advantageous embodiments are specified in the subclaims.

The vortex generator has a longitudinal direction, two fins each arranged at an angle to the longitudinal direction and extending in the longitudinal direction over a first length, and a base connecting the two fins with each other, wherein the base has a width and extending in the longitudinal direction over a second length, wherein over the entire width of the base, the second length is smaller than the first length.

The longitudinal direction corresponds to a Auslegungsanströmrichtung, ie the direction in which the vortex generator is flowed in the regular operation of the incoming air. If the vortex generator is attached to the surface of a wind turbine rotor blade, the longitudinal direction lies in a profile plane of the rotor blade. The direction pointing to a profile nose edge of the rotor blade is called forward, the direction pointing to a profile end edge is referred to as the rear. Similarly, the indication below refers to the direction toward the surface of the rotor blade and the indication above refers to the direction away from that surface.

The fins extend upwardly from the base, in particular approximately orthogonally to the surface of the wind turbine rotor blade. However, you can also deviating more or less inclined to the surface arranged be. The fins have a height that can be adapted to the thickness of a boundary layer of the flow. In particular, the height may be slightly larger than the thickness of the boundary layer. The fins may have a uniform height over their entire length. Alternatively, the height may vary over the lengthwise direction. In particular, vortex generators whose height is less at a front end than a rear end are common. In this case, the fins may be substantially trapezoidal or triangular. Deviations are possible, both with curved front, rear, upper and / or lower edges, as well as with more or less rounded corners.

A surface in which the respective fin is arranged may be flat or slightly curved. Both fins are arranged at an angle to the longitudinal direction. This angle may be, for example, in the range of 5 ° to 45 °, so that the two fins are oriented relative to each other at an angle in the range of 10 ° to 90 °. The two fins can in particular be arranged mirror-symmetrically to a longitudinal axis of the vortex generator aligned in the longitudinal direction.

A special feature of the invention is that over the entire width of the base, the second length is smaller than the first length, that in other words the base does not extend in the flow direction over the entire length of the fins. By the extension of the base in the longitudinal direction is meant the entire extent of the base in this direction, that is, from a forwardmost point of the base to a rearmost point of the base. For example, the base may be strip-shaped with parallel front and rear edges. In this case, the distance between the leading edge and the trailing edge of the base corresponds to the second length. Transverse to the longitudinal direction, the base has a width extending from one fin to the other fin. Because of the angular position of the fins For example, the base may be trapezoidal in particular when the viewing direction is directed towards the surface. Alternatively, the base can also survive laterally over the fins.

Typical dimensions of the entire vortex generator are, for example, in a range between a length of 2 cm and a width of 1.5 cm to a length of 25 cm and a width of 20 cm, the height of the fins, for example, in a range between 20% and 100% of the length can be. The base or the entire vortex generator may consist of a relatively stiff, inflexible material such as metal. A fiber composite material is an alternative. The vortex generator can be made in one piece or composed of several elements.

The invention makes use of the fact that in the case of wind turbine rotor blades the position-dependent change of the curvature of the surface in the longitudinal direction is particularly pronounced. The intended shortening of the length of the base in this longitudinal direction reduces the gaps which occur between the fastening surface and the surface of the rotor blade. The inventors have recognized that the gap dimensions that occur can be reduced to a sufficiently short base so that they can be compensated, for example, by the elasticity of a double-sided adhesive tape. For example, 1.5 mm thick tapes can be used, which due to their elasticity, can compensate for up to about 25% of their thickness. If the base is shortened so much that the size of the gaps occurring at the different attachment positions does not change by more than about 0.375 mm, then a reliable and particularly simple attachment with such an adhesive tape is possible. However, advantages also arise when using other adhesives.

In one embodiment, the second length is at most 70% of the first length. The second length may also be at most 50%, at most 40%, at most 30% or not more than 20% of the first length. By this measure, a further reduction of the gap dimensions occurring is possible, so that a reliable attachment succeeds even with large vortex generators. Experiments have shown that the size of the remaining attachment surface in spite of the shortening is sufficient in many cases.

In one embodiment, the base has a mounting surface for bonding to a surface of a wind turbine rotor blade. The attachment surface is located at an underside of the base. The attachment surface may optionally extend over the entire underside of the base or over a portion thereof, in particular over much of the total area of the underside of the base. In addition, the mounting surface may have an activated surface to ensure a particularly secure connection with the adhesive.

In one embodiment, the attachment surface has a curvature in the longitudinal direction. In principle, the mounting surface can also be flat. However, a particularly concave curvature allows a further reduction in the gap dimensions that occur, in particular if it is adapted to a mean curvature of the surface of the wind turbine rotor blade.

In one embodiment, the fins each have a central longitudinal portion, the lower edge of which is connected to the base, and a front longitudinal portion, which is arranged in front of the base in the longitudinal direction, and a rear longitudinal portion, which is arranged in the longitudinal direction behind the base , In this case, the front longitudinal portion and the rear longitudinal portion are not connected directly to the base. However, the base is in a middle position and the fins are sufficiently fixed over their entire length. An attachment of the front longitudinal section or the rear longitudinal section on the surface of the rotor blade is not required in the invention and also not provided. Regardless of this, a sealing of the free space between the longitudinal sections mentioned and the surface of the rotor blade can be useful.

In one embodiment, the front longitudinal portion is arranged in a plane and has a lower edge projecting down over the base and / or the rear longitudinal portion is arranged in a plane and has a lower edge which projects down over the base , In particular, in the case of strongly curved surfaces, the distance between the lower edges of the fins and the surface of the rotor blade can be reduced in this way, which can be aerodynamically advantageous.

In one embodiment, the lower edge of the front longitudinal section and / or the lower edge of the rear longitudinal section is curved. In particular, these edges may be adapted to a mean curvature or to a minimum curvature of the surface of the wind turbine rotor blade. The curvature can contribute to a small distance between the fin and the surface.

In one embodiment, a front longitudinal section and / or a rear longitudinal section of a fin has an angled edge section at its lower edge. The edge portion may protrude from a plane in which the longitudinal portion is arranged. In particular, it may extend from the edge to the outside, that is, away from the other fin, or to the inside, than toward the other fin. The angled edge section causes a stiffening of the fin and can counteract vibrations.

In one embodiment, the vortex generator is manufactured by punching out a flat material and then bending the two fins relative to the base. This type of production is particularly easy. By bending a high dimensional stability is achieved. The flat material may in particular be a sheet, for example made of aluminum or steel, in particular stainless steel. The flat material may have a uniform thickness, for example in the range of 0.3 mm to 3 mm. Optionally, the aforementioned edge portions at the lower edges of front and / or rear longitudinal portions of the fins can also be formed by simple angling.

In one embodiment, a double-sided adhesive tape is adhered to the mounting surface. The adhesive tape may have an elastic layer, in particular made of foam and / or with a thickness of, for example, 1 mm or more. This allows the already explained compensation of different gaps. The vortex generator can be particularly easily glued to the surface of a wind turbine rotor blade without further preparation.

In one embodiment, the double-sided adhesive tape extends over the entire width of the attachment surface or the base and / or over the entire second length. This allows a full-surface bonding.

In one embodiment, a vortex generator according to any one of claims 1 to 11 is combined with a wind turbine rotor blade, wherein the mounting surface of the vortex generator is bonded to a surface of the wind turbine rotor blade. The bond can be made in particular with a double-sided adhesive tape.

In one embodiment, a seal is disposed between the surface and edges of the vortex generator adjacent the surface. The seal can be performed, for example, with a sealant, such as a silicone material. It may orbit around the attachment surface and / or be disposed between lower edges of the fins and the surface. On the one hand, the seal protects the bond from external influences. On the other hand, accumulation of soiling can be prevented. Furthermore, the seal leads to an optimal aerodynamic shape.

In one embodiment, a plurality of identically shaped vortex generators are bonded to the surface at different positions on the surface where the surface has different curvatures. An individual adaptation of the geometry of the vortex generators to differently curved surfaces is not necessary in the invention.

Figur 1

ein Windenergieanlagenrotorblatt mit Vortex-Generatoren

Figuren 2-6

jeweils ein Ausführungsbeispiel eines Vortex-Generators, im linken Teil der Figur in einer Ansicht von der Seite und im rechten Teil der Figur in einer Ansicht von oben;

Figuren 7 und 8

jeweils ein Stanzteil zur Herstellung eines Vortex-Generators in einer Draufsicht.

The invention will be explained in more detail with reference to embodiments shown in FIGS. Show it:

FIG. 1

a wind turbine rotor blade with vortex generators

Figures 2-6

in each case an embodiment of a vortex generator, in the left part of the figure in a view from the side and in the right part of the figure in a view from above;

FIGS. 7 and 8

in each case a stamped part for producing a vortex generator in a plan view.

All figures are schematic. An arrow in each figure indicates the longitudinal direction 12 corresponding to the design flow direction.

FIG. 1 1 shows an exemplary wind turbine rotor blade 100 having a rotor blade root portion 106 with a substantially circular cross-section, a transition region 107 and a profile region 108. The wind turbine rotor blade 100 has a pressure side 109 and an opposite suction side 110 with respect to a longitudinal extension direction 111. The rotor blade 100 is formed substantially hollow inside. On a surface 14 of the suction side 110, the rotor blade 100 has a number of vortex generators 10.

The vortex generator 10 off Fig. 2 is attached to a surface 14 of a wind turbine rotor blade 100, shown in partial section along a profile plane. It has two fins 16 and a base 18. The fins 16 each extend in the longitudinal direction 12 over a first length L1. The base 18 has a width B and extends in the longitudinal direction 12 over a second length L2, which is smaller than the first length L1.

The base 18 is strip-shaped, with the width B of the strip extending transversely to the longitudinal direction 12. In the right part of the Fig. 2 shown top view can be seen that the base 18 is a total of trapezoidal. At its lateral ends, the base 18 is connected to central longitudinal sections 20 of the fins 16. In the example of Fig. 2 is the base 18 even. On its underside, it has one of the surface 14 facing, also flat mounting surface. Between the mounting surface and the surface 14, a double-sided adhesive tape 34 is arranged.

The fins 16 have a height H which is greater at their rear end than at their front end. In front of the central longitudinal section 20, a front longitudinal section 22 is arranged, which is not directly connected to the base 18. Behind the central longitudinal section 20, a rear longitudinal section 24 is arranged, which is likewise not directly connected to the base 18. The three longitudinal sections 20, 22, 24 of the fins 16 are each arranged in a plane which is oriented perpendicular to the base or surface 14 of the wind turbine rotor blade and at an angle α to the longitudinal direction 12th

In the right part of the Fig. 2 it can be seen that the vortex generator 10 is mirror-symmetrical to a longitudinal axis 26. This applies in particular to the arrangement of the two fins 16.

The front longitudinal section 22 has a lower edge 28. The central longitudinal section 20 has a lower edge 30, at which the fin 16 merges into the base 18. The rear longitudinal section 24 has a lower edge 32. The lower edges 28, 30, 32 are in the embodiment of Fig. 2 lined up in a straight line.

The vortex generator 10 off Fig. 3 largely corresponds to that of Fig. 2 , The only difference is that the front longitudinal sections 22 and the rear longitudinal sections 24 of the fins 16 each have an edge section 36 which extends inwardly from the respective lower edge 28 or 32 of the respective longitudinal section 22, 24. These edge portions 36 are arranged in the same plane as the base 18th

The vortex generator 10 off Fig. 4 also largely corresponds to that Fig. 2 , The only difference is that the lower edges 28 and 32 of the front longitudinal sections 22 and the rear longitudinal sections 24 of the fins 16 are curved. They run at approximately uniform distance from the surface 14. These lower edges 28, 32 are down over the base 18 via.

The vortex generator 10 off Fig. 5 largely corresponds to that of Fig. 3 , The only difference is that the lower edges 28, 32 of the front longitudinal section 22 and the rear longitudinal section 24 of the fins 16, similar to the vortex generator 10 from Fig. 4 survive down over the base 18. In contrast to the vortex generator 10 off Fig. 4 However, they run straight.

The vortex generator 10 off Fig. 6 largely corresponds to that of Fig. 4 , The only difference is that not only the lower edges 28, 32 of the front longitudinal section 22 and the rear longitudinal section 24 of the fins 16 are curved, but also that the base 18 has a curvature. This curvature of the base 18 corresponds to a mean curvature of the surface 14 of the wind turbine rotor blade. In addition, a seal 38 is shown, which fills a space between the edges of the vortex generator 10 and the surface 14.

Fig. 7 shows a stamped part 40 made of sheet steel, which has a base 18 and two fins 16. Middle longitudinal sections 20 of the fins 16 go to the dashed lines, the course of which corresponds to the lower edges 30 of the central longitudinal sections 20, in the base 18 via. It is intended to angle the fins 16 along the dashed lines relative to the base 18. The lower edges 28 and 32 of the front longitudinal sections 22 and rear longitudinal sections 24 of the fins 16 are curved, so that by this raising of the fins 16, a vortex generator 10 having a shape according to Fig. 4 arises. Between the central longitudinal sections 20 and the respectively adjacent, front or rear longitudinal sections 22, 24, the stamped part 40 has recesses 42. These recesses 42 extend into the plane of the fins 16.

In the stamped part 40 off Fig. 8 the lower edges 28, 32 of the front longitudinal sections 22 and the rear longitudinal sections 24 of the fins 16 are rectilinear. Adjacent to these lower edges 28, 32 edge portions 36 which can be angled inwardly or outwardly relative to the plane of the longitudinal sections 22, 24. If they are angled inward, this creates a vortex generator 10, the shape of the vortex generator 10 from Fig. 5 equivalent.

List of reference numbers:

10

Vortex generator

12

longitudinal direction

14

surface

16

fin

18

Base

20

middle longitudinal section

22

front longitudinal section

24

rear longitudinal section

26

longitudinal axis

28

lower edge of the front longitudinal section 22

30

lower edge of the central longitudinal section 20

32

lower edge of the rear longitudinal section 24

34

double-sided adhesive tape

36

edge section

38

sealing

40

stamping

42

recess

100

Wind turbine rotor blade

106

Rotor blade root area

107

Transition area

108

Focus area

109

pressure side

110

suction

111

Longitudinal extension

L1

first length

L2

second length

B

width

Claims (15)

A vortex generator (10) having a longitudinal direction (12), two fins (16) each arranged at an angle α to the longitudinal direction (12) and extending in the longitudinal direction (12) over a first length L1, and a Base (18) interconnecting the two fins (16), the base (18) having a width B and extending in the longitudinal direction (12) over a second length L2, characterized in that over the entire width B of the Base (18), the second length L2 is smaller than the first length L1. Vortex generator (10) according to claim 1, characterized in that the second length L2 is at most 70% of the first length L1. Vortex generator (10) according to claim 1 or 2, characterized in that the base (18) has a mounting surface (19) for bonding to a surface (14) of a wind turbine rotor blade. Vortex generator (10) according to one of claims 1 to 3, characterized in that the fastening surface (18) in the longitudinal direction (12) has a curvature. Vortex generator (10) according to one of claims 1 to 4, characterized in that the fins (16) each have a central longitudinal portion (20) whose lower edge (30) is connected to the base (18) and a front A longitudinal portion (22) disposed in front of the base (18) in the longitudinal direction (12) and a rear longitudinal portion (24) disposed behind the base (18) in the longitudinal direction (12). A vortex generator (10) according to claim 5, characterized in that the front longitudinal portion (22) is arranged in a plane and has a lower edge (28) which projects down over the base (18) and / or that Rear longitudinal portion (24) is arranged in a plane and having a lower edge (32) which projects down over the base (18). Vortex generator (10) according to claim 5 or 6, characterized in that the lower edge (28) of the front longitudinal section (22) and / or the lower edge (32) of the rear longitudinal section (24) is curved. Vortex generator (10) according to one of claims 5 to 7, characterized in that the lower edge (28) of the front longitudinal section (22) and / or the lower edge (32) of the rear longitudinal section (24) at an angle to the lower edge (30) of the central longitudinal portion (20) is arranged. Vortex generator (10) according to one of claims 1 to 8, characterized in that a front longitudinal section (22) and / or a rear longitudinal section (24) of a fin at its lower edge (28, 32) has an angled edge portion (36). having. Vortex generator (10) according to one of claims 1 to 9, characterized in that the vortex generator (10) by punching a flat material and then bending the two fins (16) relative to the base (18) is made. Vortex generator (10) according to one of claims 1 to 10, characterized in that a double-sided adhesive tape (34) is adhered to the mounting surface. Vortex generator (10) according to claim 11, characterized in that the double-sided adhesive tape (34) extends in the longitudinal direction (12) over the entire width of the mounting surface or the base and / or over the entire second length L2. Wind turbine rotor blade (100) with a vortex generator (10) according to one of claims 1 to 12, the mounting surface of which is glued to a surface (14) of the wind turbine rotor blade. Wind turbine rotor blade (100) according to claim 13, characterized in that between the surface (14) and the surface (14) adjacent edges of the vortex generator (10) has a seal (38) is arranged. Wind turbine rotor blade (100) according to claim 13 or 14, characterized in that a plurality of identically shaped vortex generators (10) at different positions of the surface (14), at which the surface (14) has different curvatures, with the surface (14). are glued.

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